Gene Pool and Gene Frequency — Prelims Strategy

Prelims Strategy

To excel in NEET questions on Gene Pool and Gene Frequency, a multi-pronged strategy is essential. For numerical problems, the key is to correctly identify what is given and what needs to be calculated.

Always start by identifying the frequency of the homozygous recessive genotype ($q^2$) if the recessive phenotype frequency is provided, as this is often the entry point into the Hardy-Weinberg equations.

From $q^2$, calculate $q$ (recessive allele frequency) by taking the square root. Then, use $p+q=1$ to find $p$ (dominant allele frequency). Finally, use $p^2$, $2pq$, or $q^2$ to find the required genotype frequencies.

Pay close attention to whether the question asks for allele frequency or genotype frequency. For conceptual questions, memorize the five conditions for Hardy-Weinberg equilibrium and the five factors that disrupt it.

Understand the *mechanism* by which each factor (mutation, gene flow, genetic drift, natural selection, non-random mating) alters gene frequencies. Be wary of trap options that confuse population-level concepts (gene pool) with individual-level concepts (genome) or assume dominant alleles are always more frequent.

Practice a variety of MCQs, including those that require interpreting scenarios of evolutionary change.